Mycoplasma hyopneumoniae (also referred to as M. hyopneumoniae) is the etiologic agent of swine mycoplasmal pneumonia. The disease causes a chronic cough, dull hair coat, retarded growth and unthrifty appearance lasting several weeks. Characteristic lesions of purple to gray areas of consolidation, particularly in ventral apical and cardiac lobes are observed in infected animals. Although the disease causes little mortality, affected swine are often prone to secondary infections by opportunistic pathogens, resulting in death or stress. (R. F. Ross, Mycoplasmal diseases, pp. 436-444, in A. D. Laman, et al., (eds.) Diseases of Swine, Iowa State University Press, 1986).
The disease is believed to be one of the most important causes of disease-associated loss in swine (Whittlestone, pp. 133-176, in Tully and Whitcomb (eds.), The Mycoplasma Vol 2: Human and Animal Mycoplasmas, New York, Academic Press, (1979)). The disease generally results in inefficient weight gainers, and in stunted and sickly animals. Also, affected swine are often prone to secondary infection by opportunistic organisms (Burch, Pig America pp. 26-27, December, 1982). The economic impact of the disease is significant. Economic losses alone have been estimated at between 200 to 250 million dollars annually.
Mycoplasma hyopneumoniae is a slow growing, fastidious bacterium that lacks a cell wall. It is frequently difficult to isolate from the respiratory tract due to Mycoplasma hyorhinis, a common secondary agent also located in the respiratory tract. The disease is spread by aerosol, produced by coughing, and by direct contact from an affected or convalescent carrier swine. Mingling of infected animals and uninfected animals results in early and frequent reinfection. Infection frequently starts with infection of piglets by carrier sows at farrowing.
Due to herd management techniques, infection may not become evident until later in life. Additional infection usually is observed after weaning when pigs are pooled. Overt disease is normally observed in pigs at six weeks of age or older. Growth rates and feed conversion rates are markedly reduced in affected animals. Existing treatments using antibiotics are expensive and require prolonged use. Animal reinfection remains a problem.
Thus, vaccines are presently the most effective method for avoiding infections and their consequences. There have been numerous attempts to provide a vaccine for protecting swine against Mycoplasma hyopneumoniae infection. Several investigators have disclosed vaccines comprising recombinantly produced surface antigens of Mycoplasma hyopneumoniae, Schaller et al., U.S. Pat. No. 4,894,332, issued Jan. 16, 1990; European Patent Publication No. 283,840, published Sep. 28, 1988. PCT Publication No. WO 86/00019, published Jan. 3, 1986, discloses a Mycoplasma hyopneumoniae vaccine comprising exclusively Mycoplasma hyopneumoniae plasma membranes, free of other cell components. Etheridge et al., Res. Vet. Sci. 33:188 (1982), found incomplete protection against lung colonization by Mycoplasma hyopneumoniae when a live vaccine was given intravenously, subcutaneously, or intraperitoneally. Kristensen et al., Am. J. Vet. Res. 42:784 (1981), found no protection of swine against mycoplasmal pneumonia after injection with heat-inactivated Mycoplasma hyopneumoniae. Ross et al., Am. J. Vet. Res. 45:1899 (1984), found that use of Mycoplasma hyopneumoniae extracts prepared by a freeze-thaw procedure to immunize swine, provided only variable protection, and in some instances, enhanced lesion development was noted in immunized swine. These investigators also studied a whole-cell vaccine prepared by formalin inactivation. Formalin inactivation significantly hindered the protective immunogenicity of Mycoplasma hyopneumoniae, and this vaccine was not effective. Yoshioka et al., U.S. Pat. No. 3,917,819 (issued Nov. 4, 1975) discloses several killed Mycoplasma vaccines comprising Mycoplasma inactivated with formalin, including an inactivated vaccine for Mycoplasma hyopneumoniae. Chung-Nan European Patent Publication 571,648 disclosed an M. hyopneumoniae vaccine based on the highly proliferative and antigenic strain PRIT-5.
Vaccines based on inactivated virulent Mycoplasma hyopneumoniae strains are commercially available. Fort Dodge Animal Health (FDAH) markets Mycoplasma hyopneumoniae bacterin under the name Suvaxyn® and Respifend® Mycoplasma hyopneumoniae for use as a vaccine to protect healthy swine against clinical signs caused by Mycoplasma hyopneumoniae. This bacterin vaccine is recommended as a two-dose vaccine for pigs at least one-week old, with the second dose two to three weeks after the first vaccination.
The M. hyopneumoniae J strain is a non-pathogenic strain with reduced capacity to adhere to porcine cilia and, therefore, to cause disease. Castro et al., Veterinary Microbiology 116:258-269 (2006) and Vasconcelos et al, J. Bacteriol. 187(16):5568-5577 (2005) (describing the complete genome sequence of M. hyopneumoniae J strain (ATCC 25934)). Genomic comparisons between pathogenic and nonpathogenic strains (J strain) have revealed variations in surface proteins, including cilium adhesin, that are believed to be determinative of relative pathogenic properties between M. hyopneumoniae strains. Vasconcelos et al. (2006) and Djordjevic et al., Infection and Immunity 72(5):2791-2802 (2004).
M. hyopneumonia expresses, on its cell surface, membranous lipoproteins, particularly the P46, P65, and P97 proteins, which carry species-specific antigenic determinants. Recently, Bouh et al. described monoclonal antibodies to P46 and P65 of live avirulent M. hyopneumoniae reference J strain ATCC 25934. Clin. Diag. Lab. Immunology 10(3):459-468 (2003). Blank and Stemke described a physical and genetic map of M. hyopneumoniae strain J genome, Can. J. Microbiol. 46:832-840 (2000), and Wilton et al. described the screening of expression libraries generated from the non-pathogenic M. hyopneumoniae J strain and the screening of those libraries with porcine hyperimmune antiserum against M. hyopneumoniae. 
There is a need for compositions, including immunogenic or vaccine compositions, made from live adjuvanted avirulent Mycoplasma hyopneumoniae, which compositions provide efficacy against virulent strains of M. hyopneumoniae. The citation of any reference herein should not be deemed as an admission that such reference is available as prior art to the instant invention.